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CN-121974863-A - Preparation method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine from clothianidin wastewater

CN121974863ACN 121974863 ACN121974863 ACN 121974863ACN-121974863-A

Abstract

The invention provides a preparation method of 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by clothianidin wastewater, which relates to the technical field of chemical preparation and comprises the following steps of Sp1 preparing reaction liquid 1, standing clothianidin acidic wastewater for layering, taking upper acidic wastewater, and carrying out reduced pressure distillation to obtain acidic distillate and mother liquor; and adding dropwise caustic soda into the mother liquor, regulating the pH value to be neutral, then continuing to add dropwise caustic soda, regulating the pH value to be alkaline, and heating and absorbing ethylamine to obtain a reaction liquid 1. According to the method, the thiamethoxam acidic wastewater is subjected to targeted treatment, and ethylamine in the thiamethoxam acidic wastewater is effectively recycled and directly used for synthesizing the downstream triazine compound, so that the defect that a large amount of high-salt wastewater is generated in the traditional neutralization treatment is overcome, the direct discharge amount of strong acid wastewater is reduced, the risks of water acidification and ammonia nitrogen pollution are reduced, and the environment is protected.

Inventors

  • DAI BAIXIONG
  • ZHANG JIANGUANG
  • Qiao Feili
  • LU WEI
  • WANG NIAN
  • CHEN YANSHENG
  • WANG BO

Assignees

  • 内蒙古犇星化学有限公司

Dates

Publication Date
20260505
Application Date
20251229

Claims (10)

  1. 1. The method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by using clothianidin wastewater is characterized by comprising the following steps: Sp1 is used for preparing a reaction liquid 1, namely, thiamethoxam acidic wastewater is subjected to standing and layering, upper acidic wastewater is taken, reduced pressure distillation is carried out to obtain acidic distillate and mother liquor, alkali is added into the mother liquor in a dropwise manner, the pH value is regulated to be neutral, then alkali is added into the mother liquor in a dropwise manner, the pH value is regulated to be alkaline, and ethylamine is heated and absorbed simultaneously to obtain the reaction liquid 1; Sp2 is used for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine, which comprises the steps of adding clear water into a reaction container, adding paraformaldehyde and methyl nitroguanidine at one time, heating to a preset temperature, then dropwise adding the reaction solution 1, controlling the dropwise adding rate and the reaction temperature, carrying out heat preservation reaction after dropwise adding, and cooling, crystallizing and separating after the reaction is finished to obtain the 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine.
  2. 2. The method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by using clothianidin wastewater according to claim 1, wherein in Sp1, the upper layer acid wastewater dosage of clothianidin acidic wastewater is 500g, 250g acid distillate with pH less than 1 and 250g mother liquor are obtained after reduced pressure distillation, the standing layering time is 1-2 hours, the vacuum degree of reduced pressure distillation is 0.08-0.1MPa, and the distillation temperature is 50-70 ℃.
  3. 3. The method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by using clothianidin wastewater according to claim 1, wherein in Sp1, 80g of 30% liquid alkali is firstly dripped into the mother liquor, the pH is adjusted to 6, then 106g of 30% liquid alkali is continuously dripped into the mother liquor, the pH is adjusted to 9-10, at the moment, the kettle liquid starts to become turbid, the kettle liquid is heated to 90 ℃ to absorb ethylamine, and the dripping speed of the liquid alkali is 10-30g/min so as to avoid uneven precipitation caused by overhigh local pH.
  4. 4. The method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by using clothianidin wastewater according to claim 1, wherein in Sp1, a falling film absorption system is adopted in the dropping liquid alkali adding process, the circulation flow of the falling film absorption system is 5-10L/h, and the height of an absorption tower is 1-2m, so that the recovery efficiency of ethylamine is improved.
  5. 5. The method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by using clothianidin wastewater according to claim 1, wherein in Sp2, the amount of clear water is 250g, the amount of paraformaldehyde is 65g, the amount of methyl nitroguanidine is 112.5g, the molar ratio of the paraformaldehyde to the methyl nitroguanidine is 2:1-3:1, the stirring speed after one-time addition is 100-200r/min, and the heating rate is 2-5 ℃ per min.
  6. 6. The method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by using clothianidin wastewater according to claim 1, wherein in Sp2, after the temperature is raised to 45 ℃, the reaction liquid 1 starts to be added dropwise, the dropwise adding amount of the reaction liquid 1 is 72.5g, the dropwise adding rate is 20g/h, the dropwise adding time is 2.5-3 hours, and the dropwise adding is controlled by adopting a constant-speed pump so as to ensure that the reaction liquid 1 is added uniformly and avoid overhigh local concentration.
  7. 7. The method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by using clothianidin wastewater according to claim 1, wherein in Sp2, in the process of dropwise adding reaction liquid 1, the reaction temperature is controlled to be 60+/-1 ℃, the heat preservation temperature is controlled to be 60+/-1 ℃ after dropwise adding, the temperature control adopts a water bath heating mode, the fluctuation range is not more than +/-2 ℃, and if the central control index does not reach the standard, the heat preservation time can be prolonged by 0.5-1 hour.
  8. 8. The method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by using clothianidin wastewater according to claim 1, wherein in Sp2, sampling and monitoring are carried out every other hour in the reaction process, the central control index is that the content of methyl nitroguanidine is <1%, and the content of 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine is >98%, and the monitoring is quantitatively analyzed by adopting high performance liquid chromatography or gas chromatography so as to adjust reaction parameters in real time.
  9. 9. The method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by using clothianidin wastewater according to claim 1, wherein in Sp2, after the reaction is finished, water bath is cooled to 40 ℃, 20g of water is added, meanwhile, the stirring rotation speed is reduced to 30r/min, the temperature is continuously reduced to 5 ℃, suction filtration and centrifugal separation are carried out after the temperature is kept for 30min, the cooling rate is controlled to be 1-5 ℃/min so as to promote uniform precipitation of crystals, and filter cakes can be further washed for 1-2 times after the separation.
  10. 10. The method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by using clothianidin wastewater, which is characterized in that the method realizes the synthesis of 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by recycling ethylamine in clothianidin wastewater, the recovery rate of the ethylamine is more than 90%, the reaction vessel is a three-mouth bottle or an industrial reaction kettle with stirring, a precise temperature controller is adopted for temperature control in the method, and pH adjustment is monitored by using an online pH meter.

Description

Preparation method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine from clothianidin wastewater Technical Field The invention relates to the technical field of chemical preparation, in particular to a preparation method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by clothianidin wastewater. Background Along with the rapid development of pesticide industry, clothianidin is widely applied in the global field as a high-efficiency and low-toxicity neonicotinoid insecticide, and the production scale of clothianidin is continuously enlarged. However, clothianidin synthesis processes typically involve multi-step reactions of nitromethane, formaldehyde, ethylamine, hydrochloric acid, etc., resulting in the production of large amounts of acidic wastewater. The wastewater contains high-concentration hydrochloric acid, ethylamine and other organic residues, has the characteristics of strong acidity (pH < 1), high ammonia nitrogen and high COD, and can cause serious environmental pollution if being directly discharged, and meanwhile, the loss of useful components such as ethylamine and the like also increases the raw material consumption and the production cost. At present, the industrial treatment of clothianidin wastewater mainly adopts traditional methods such as neutralization-biochemical treatment, incineration or external critical waste disposal, and the like, while 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine (called triazine compound for short) is used as a key intermediate of clothianidin and other nitroguanidine pesticides, and the synthesis of the clothianidin pesticide generally depends on fresh formaldehyde solution, methyl nitroguanidine and external ethylamine aqueous solution for condensation reaction. However, the following key problems still exist in the production of clothianidin and synthesis of triazine compounds in the prior art: 1. high waste water yield, strong acidity and high environmental risk. The clothianidin synthesis process is accompanied with a plurality of tons of strongly acidic wastewater per ton of products, contains a large amount of hydrochloric acid and ethylamine, and directly neutralizes the products to consume a large amount of alkali liquor, also generates high-salt wastewater, increases the burden of subsequent biochemical treatment, and if the products are improperly treated, water acidification and ammonia nitrogen exceeding are easily caused, so that the ecological environment is greatly threatened. 2. The valuable component ethylamine is difficult to recover and has low utilization rate. The existing wastewater treatment technology focuses on standard emission, but lacks efficient recovery means for ethylamine dissolved in wastewater, so that the ethylamine runs off along with the wastewater, the raw material purchasing cost of clothianidin and downstream triazine compounds is increased, and the overall ammonia nitrogen load and the environmental pollution risk are increased. 3. The synthesis of triazine compounds relies on exotic ethylamine, the cost of raw materials is high and the supply chain is unstable. The traditional triazine synthesis route needs to purchase ethylamine aqueous solution alone as a key raw material, the ethylamine price fluctuation is large, certain safety risks (such as easy volatilization and flammability) exist in storage and transportation, and meanwhile, the energy consumption and the waste production amount in the production process are increased due to the additional introduction of fresh raw materials, so that the internal recycling of resources cannot be realized. Therefore, a method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by using clothianidin wastewater is needed to solve the problems in the prior art. Disclosure of Invention Technical problem to be solved Aiming at the defects of the prior art, the invention provides a preparation method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by clothianidin wastewater, which solves the problems of the prior art. Technical proposal The invention aims at realizing the purposes by adopting the following technical scheme that the method for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine by using clothianidin wastewater comprises the following steps: Sp1 is used for preparing a reaction liquid 1, namely, thiamethoxam acidic wastewater is subjected to standing and layering, upper acidic wastewater is taken, reduced pressure distillation is carried out to obtain acidic distillate and mother liquor, alkali is added into the mother liquor in a dropwise manner, the pH value is regulated to be neutral, then alkali is added into the mother liquor in a dropwise manner, the pH value is regulated to be alkaline, and ethylamine is heated and absorbed simultaneously to obtain the reaction liquid 1; Sp2 is used for preparing 1, 5-dimethyl-2-nitroimino-hexahydro-1, 3, 5-triazine, which comprises